Virginia Republicans gained ground for the third consecutive election Tuesday, continuing a stream of success since President Obama won the state in 2008.

Yet despite the GOP’s apparent takeover of the state Senate — and with it, complete control of the levers of government — Tuesday’s results are ambiguous enough that neither party can claim a clear advantage heading into next year’s presidential contest and the expected marquee U.S. Senate race between former governors George Allen (R) and Timothy M. Kaine (D).

“This wasn’t as sweeping a Republican wave as some had anticipated,” said David Wasserman, an editor at the nonpartisan Cook Political Report. “That said, [Tuesday] night’s results provide little consolation to Democrats that there’s been any kind of recovery since last year.”

Republicans captured the governor’s mansion in 2009 and ousted three incumbent congressional Democrats last year. The raw numbers from Tuesday point to a continued Republican surge, as the party built a historically large majority in the House of Delegates and claimed control of the Senate on Wednesday.

The chamber is now split 20-20, but roughly 60 percent of voters statewide backed Republicans in Senate races, suggesting that Democrats were spared from larger losses only because they drew a cleverly gerrymandered redistricting map. (Republicans benefited from a similar advantage in the state House, where they drew the lines.)

Yet Democrats held their own in many of the state’s traditional swing regions, the counties that will help determine next year’s U.S. Senate and White House contests. The party kept its Senate seats in Northern Virginia and Hampton Roads, the two largest population centers, and showed resilience in key individual counties.

In Fairfax, all nine Democratic senators or candidates who represent portions of the county won their races, and the party maintained its 7-3 edge on the Fairfax Board of Supervisors. Farther south, Democrats were also crowing about scoring an upset victory in the race for Henrico County commonwealth’s attorney.

But Republicans held their current Senate seats across the state, all with double-digit victory margins. Republicans pointed to a strong showing in Loudoun County, where they eviscerated Democrats on the Board of Supervisors, taking a 9-0 advantage, and won races for sheriff and commonwealth’s attorney.

When Obama won Virginia in 2008 — the first Democrat to do so in four decades — he rode majorities in Fairfax, Loudoun, Prince William and Henrico. To win the state again next year, Wasserman said, he’ll have to “run up the score” in those regions to counter likely lopsided margins against him in rural areas.

Democrats say they know the challenge that lies ahead.

“We feel very good about our chances in Virginia in 2012 and understand it will be a competitive election,” said Marianne von Nordeck, the Obama campaign’s Virginia spokeswoman. “We are also not starting from scratch in the state, as we’ve had nearly 1,600 events across the commonwealth in the last eight months, and we are continuing to ramp up our efforts across Virginia and plan to have a robust and historic operation next year.”

In much of the country, voters are pessimistic about the economy and angry at incumbents in both parties. Virginia is unusual, in that Gov. Robert F. McDonnell (R) retains solid approval ratings and the state has a lower unemployment rate and a more optimistic electorate than most other states.

Even as Republicans have notched victories in recent cycles, all available survey data point to a competitive 2012.

Noting that nearly every public poll of the Allen-Kaine race shows a dead heat, Kaine spokeswoman Brandi Hoffine said “that’s the expectation we entered this race with, and that’s the expectation we still have coming out of yesterday, though we also feel good about some results in key places.”

In the final stretch of this year’s campaign, several Democrats in key state legislative races distanced themselves from Obama, and some also sought to highlight their good relationships with McDonnell.

“It’s clear that of the Democrats that were able to hold on, they did not run as Democrats,” said Dan Allen, a senior adviser to George Allen’s campaign. “Tim Kaine is not going to have that luxury because of his special relationship with the president and supporting his failed policies.”

But Mark Rozell, a public policy professor at George Mason University, said Tuesday’s results seemed to confirm that races are typically decided by “local issues and personalities” rather than national or even statewide trends.

“That’s an important lesson for 2012,” Rozell said. “I would not be terribly surprised, for example, if Obama lost the state and Kaine defeated Allen.”